Optical Determination of Stress. 

 Table IV. 



747 







Abscissae, inc 



les. 







0. 



025. 



05. 



0-75. . 



Distance of 



neutral axis 



from zero line 



2 00. 



00 . 



5 § 











ms. 





+1750 





+ 1190 





T35 



-960 





+2320 





+1410 





1-35 



-1070 



■as 



l/l 00 



+2880 

 +3330 



+2540 



+2880 



+ 1880 



+ 1520 



1-39 

 1-45 



-1190 

 -1470 



DQ &i 



+3560 



+3450 



+3160 



+2200 



T47 



-1640 



Fig. 3. 



properties of the material, which showed itself when the load 

 was removed by its faint doubly refracting power. The 

 highest values of the stress are therefore not correct, owing 

 to their values having been obtained by comparison with a 

 test piece differing in optical condition from the object. 



The position of the neutral axis for the lower loadings 

 agrees very well with that given by calculations using the 

 ordinary formula for beams. It is also worthy of note that 

 the neutral axis moved away from the tension side as the 

 load increased — a result* which agrees with theoretical 

 determinations. 



* Love's ' Theory of Elasticity,' p. 349. 



